Blood-Brain Barrier Concepts and Drug Delivery

Question-and-answer flashcards covering the blood-brain barrier, its function, drug delivery challenges, and related strategies.

What is the blood-brain barrier (BBB) and its main function?

A protective layer of tightly joined endothelial cells between the blood vessels and the brain, highly selective, keeping harmful pathogens out while allowing essential molecules like glucose, oxygen, and water to pass.

Why is the BBB described as permeable but highly selective?

It permits passage of certain small or essential molecules but restricts most other substances from entering the brain.

What structural feature forms the BBB in brain vessels?

Specialized endothelial cells packed tightly to form junctions that regulate passage into brain tissue.

Approximately what percentage of drugs are blocked by the BBB when delivered orally or intravenously?

About 95 percent.

What is the Trojan horse approach in BBB drug delivery?

Attaching a drug to a molecule (often an antibody) that can cross the BBB by receptor-mediated transport, effectively 'tricking' the barrier.

How does the Trojan horse approach enable brain drug delivery?

The drug-antibody conjugate binds receptors on the blood side, activating transport so the conjugate crosses the barrier and unloads the drug in the brain.

Other strategies to deliver drugs to the brain mentioned besides the Trojan horse?

Using engineered viruses for delivery and applying ultrasound with microbubbles to temporarily open parts of the BBB.

How does ultrasound-assisted opening of the BBB work?

Microscopic bubbles are injected; focused ultrasound vibrates them at the target brain area, opening the barrier for a few hours before it reseals.

What evidence links the gut microbiome to BBB integrity?

Studies show gut-residing microbes can influence BBB integrity, and changes in microbiome composition over time may affect BBB strength.

Which conditions are associated with defective BBBs mentioned in the notes?

Epilepsy and multiple sclerosis, with defects traced to a single set of genes.

How could genetic understanding of BBB defects inform treatments?

It could help develop methods to either open the BBB for drug delivery or strengthen its integrity, aiding neurological disease therapies.

What is a long-term goal highlighted regarding brain drug delivery?

Mastering the ability to deliver drugs to the brain in low doses to improve efficacy and reduce side effects.